Link between air pollution and breast cancer discovered

Women living in areas that experience high levels of pollution could be at a higher risk of breast cancer, according to a new study. Research has suggested that increased exposure to soot particles could lead to denser breast tissue, which is one of the strongest risk factors linked to breast cancer.

Those with dense breast tissue are up to six times more likely to develop some form of breast cancer. This suggests that those in city areas could be at high risk of the disease, whether there is a family history of breast cancer or not.

Researchers from the University of Florida, US, looked at 279,967 women to discover if there was a link between pollution and breast cancer. This is the first study to assess the correlation between air pollution and breast density.

They discovered that women who have dense breast tissue were around 19 per cent more likely to live in areas that experience high levels of fine particle air pollution. Fine particle pollution - called PM2.5 - is able to penetrate into people's systems more deeply, which can cause a number of health concerns.

The study revealed that each one unit rise in PM2.5 increased the chance of a woman having dense breast tissue by four per cent. This could also be an indication of the reason behind geographic breast cancer patterns, according to the researchers.

Dr Lusine Yaghjyan, leader of the study, said: "Our findings suggest that previously reported geographic variation in breast density could, in part, be explained by different air pollution patterns in urban and rural areas.

"Breast density is a well-established and strong breast cancer risk factor so future studies are warranted to determine if the observed associations are causal, which if confirmed may have implications for risk prevention."

It is thought that increases in PM2.5 impact the body's hormone levels, which can trigger different tissue types in the breast to start growing. Dense breast tissue tends to contain less fat, but more glandular tissue, which increases the chance of cells becoming cancerous.

On top of this, cancer in dense breast tissue is often harder to detect with standard breast screenings. This can mean that women only realise they have breast cancer when they start experiencing symptoms, which can make it harder to treat.